The present invention relates to a method and a correspondingly configured device for transmitting data of a subscriber-specific control channel in a radio system. In particular, the present invention relates to such a method and a correspondingly configured device for transmitting data of a subscriber-specific control channel, including different symbols with control functions (such, as for example, symbols for evaluating the transmission characteristic of the respective transmission channel, symbols for power regulation or symbols with details of format information) in a radio system; in particular, a mobile radio system.
The functionality of a transmitter or receiver, such as a mobile station or a base station in a mobile radio system, is generally described in radio systems in the form of a layer model, wherein the various functionalities of the respective transmitter or receiver are assigned to different layers. In radio systems, data of higher layers (layers 2, 3 or higher) is transmitted via the air interface (layer 1). It is characteristic of radio systems that the air interface of the respective transmitter or receiver represents the bottleneck in respect of data rate (kbit/s) and transmission capacity (bit/s/Hz). New radio systems, therefore, have to be designed and operated so that the air interface is configured as optimally as possible. Optimization criteria here can, for example, be the maximum data rate of one or more subscribers, the spectral capacity of an individual radio cell or the system as a whole, etc. Adaptive configurability of the air interface is desirable here, as optimum or optimized configuration of the air interface depends on many parameters, such as the environment or characteristic of the transmission channels, the nature of the radio cells, the nature of the multiple access method used (TDD (Time Division Duplex) or FDD (Frequency Division Duplex)), the current speed of the respective subscriber, the data rate, the system load and the nature of the data transmission (e.g. packet-based or continuous, etc.). The configuration of the air interface here is generally subscriber-specific (dedicated) and dependent on the parameters listed above.
In UMTS (Universal Mobile Telecommunication System) mobile radio systems, a subscriber-specific control channel is used to configure the air interface of the respective receiver and is referred to as the Dedicated Physical Control Channel (DPCCH). Using this DPCCH channel, information is transmitted to the respective receiver which can use the information to configure its air interface. In particular, this DPCCH channel contains data blocks with Npilot pilot symbols for evaluating the transmission characteristic of the respective radio channel, NTPC TPC (Transmit Power Control) symbols with information for power regulation and NTFI TFI (Transmit Format Indicator) symbols with format information or for combining the services to be transmitted (voice, circuit-switched data, packet data, etc.).
Depending on the combination of the parameters listed above, different numbers of symbols are required for the individual data blocks of the DPCCH channel.
For transmission of the DPCCH channel in the FDD mode of UMTS mobile radio systems, a method is known for transmitting the DPCCH channel in the downlink (i.e., during transmission from a base station to a mobile station), including one data block each with pilot symbols, TPC symbols and TFI symbols according to a time multiplex method with the corresponding subscriber-specific data channel (dedicated physical data channel, DPDCH). In other words, data of the DPDCH channel and data of the DPCCH channel are transmitted in succession in respect of time. In the uplink (i.e., during transmission from a mobile station to a basestation), on the other hand, what is known as an I-Q multiplex combination of the DPCCH and DPDCH channels takes place.
With regard to transmission of the DPCCH channel, it already has been proposed that the number of pilot symbols, TPC symbols and TFI symbols should be configured in a variable manner. In particular, it already has been proposed that the values Npilot, NTPC, NTFI should be modified adaptively or optimized during an existing connection by a layer 2/3 signaling, which is transmitted via the DPDCH channel.
An object of the present invention is to propose an alternative method and a correspondingly configured device for transmitting data of a subscriber-specific control channel in a radio system, such as the DPCCH channel in a UMTS mobile radio system, so that the greatest possible flexibility is achieved with the transmission of data of the subscriber-specific control channel, in order to be able to respond as quickly as possible depending on the combination of the parameters disclosed above, on which the configuration of the air interface in a transmitter or receiver of the radio system depends, and to be able to achieve a correspondingly optimized configuration of the air interface.